The upcoming series of presidential debates is the candidates' last big chance to speak before audiences of millions. Political experts say that presidential races have just three defining moments when candidates can seize voters' attention and stir new interest in their campaigns. The first two such moments, the selection of running mates and the party conventions, have passed, and the final phase begins Wednesday, when President Barack Obama and Mitt Romney meet in the first of three debates in front of a national television audience. With Obama enjoying a modest lead in the polls, the first debate is widely considered the most crucial and could set the tone for the others. It is also seen as the president’s to lose. That puts much of the pressure on Romney, who has suffered a series of setbacks since the Republican National Convention in late August. "This is his final opportunity to make his case when the country is watching," said David Lanoue, a Columbus State University political scientist who has studied presidential debates. Obama was hunkered down with advisers in Nevada Monday, while Romney was prepping in Massachusetts ahead of a trip to Denver for a rally and more preparations, The Associated Press reported.
